Some types of ground, can contain layers of very soft materials like clay or peat. These may compress if loaded by overlying structures, or if the groundwater level changes, potentially resulting in depression of the ground and disturbance of foundations.

Some types of ground, can contain loosely packed sandy layers that can become fluidized by water flowing through them. Such sands can 'run', removing support from overlying buildings and causing potential damage.

Some types of ground, contain layers of material that can be dissolved by water. This can cause underground cavities to develop. These cavities reduce support to the ground above and can lead to a collapse of overlying material.